The invention relates generally to data protection, and more particularly, to methods and systems for extending the number of applications that access protected digital content in recordable media using encrypted media key blocks in the media.
Entertainment information such as music and movies is increasingly being marketed to consumers in the form of digital media such as compact discs (CDs) and digital versatile discs (DVDs). At the same time, computers and consumer devices become more advanced and allow contents in the media to be copied if the contents are not properly protected.
In an effort to prevent unauthorized copying and redistribution of digital information, content providers and device manufacturers have jointly defined standards and technologies to protect the distributed contents, such as the Content Protection for Recordable Media (CRPM) and Content Protection for Extended Media (CPXM) standards provided by the 4C Entity (www.4centity.com). These technologies are licensed by licensing entities, e.g., the 4C Licensing Authority, to manufacturers that produce the protection devices and consumer equipment incorporating the protection implementations.
The CRPM protection standard enables protected exchange of audio/visual content recorded on various portable data storage media types, including DVD, SD memory card, and compact flash media. CPRM ties the recorded content to a media on which the content is recorded and is supported by all DVD recorders released after 1999. Each recordable media includes a media ID and a number of media key blocks (MKBs) in its protected area for supporting a fixed number of applications that can access the media. When protected contents are recorded onto the media, they can be encrypted with a set of keys derived from the media ID and media key blocks. During playback, the media ID is read from the protected area and used to generate a key to decrypt the contents of the media. If the contents of the media are copied to other media, the media ID will be absent or wrong and the contents cannot be decrypted.
For SD card applications, the SD Association assigns applications to MKBs, and defines the data structures on the media that support the application. The 4C Licensing Authority further manages the licensing of CPRM adopters and provides device key sets to manufacturers of media players and recorder, and SD cards. Currently, each SD card includes a relatively small number of sixteen media key blocks that may be assigned to applications. Furthermore, providing new applications for a media requires action from both the 4C Licensing Authority and the SD Association in the application assignment process.
It is desirable to extend the number of applications that can access content in a CPRM protected media and facilitate the MKB assignment process when new applications are introduced.